The present invention relates to a method and apparatus for treating a liquid mixture in order to separate a clarified fraction therefrom, leaving a concentrated sludge fraction. The invention is particularly applicable for treating municipal or industrial waste water in order to enable such waste water to be reused for municipal, industrial or agricultural purposes.
Municipal or industrial waste water, as well as water from rivers or lakes, must first be treated in order to remove substances which may be harmful, or which cause bad taste or odour. Many techniques are known for this purpose. One technique is a sedimentation technique wherein the solid particles or other heavy substances are permitted to separate by sedimentation from the liquid mixture, but the conventional sedimentation technique requires a relatively long period of time for the solid particles or heavy substances to settle. In order to increase the rate at which the solid particles settle, a flocculent material may be added to the liquid mixture, the flocculent material tending to flock or agglomerate with the solid particles thus enhancing the settling of the solid particles. However, relatively long periods of time are required even when using such flocculent materials.